Union Pacific set in the 1920s would be a good route before they had challengers and big boys or FEFs and so the players can see the plains of Nebraska. The locomotive for passenger service would be the 7000 Class 4-8-2s Build: 1922-1924 Units: 60 Duties: Passenger The freight locomotive would be the 9000 Class 4-12-2s which were the largest non articulated locomotives in the world. Build: 1926-1930 Units: 88 Duties: Freight
I'll do some research on different types of locomotives for the Union Pacific like 2-8-2s, 4-6-2s, and 4-6-0s.
An amazing route with little bit of everything. And an 0-6-0 would most likely be assigned switching duties.
I also did a little bit of research and the CB&Q (Burlington Route) also ran in Nebraska and If you want to do some research yourself to correct me if I'm wrong.